There is an existing type of induction motor known as a brushless doubly fed induction motor (BDFIM), which has two sets of stator windings for operation with two p-poles and two q-poles. The rotor winding has a two-pole (p+q) nested cage. The existing extended rotor cage technology has drawbacks associated with a type of energy transfer known as cluttered energy transfer. It utilizes a drive with a relatively narrow speed range and not insignificant energy losses.
There is a need for a lower than synchronous speed drive having a wider speed range. To provide such a drive, it is necessary to control the power which is related to the slip of the rotor at speeds lower or higher than the speed of the stator rotating field. This would reduce energy loss and lower the cost for adjustable speed motor drives and power generation.